With Direto: - if you use our my e-training app, you have to insert your circumference value - if you use a non elite device or app, you have to insert your circumference divided by 12.1 - calibration option is in advanced configuration of my e-training app (doesn't appear if you have selected and e...

Don't worry about the calibration value, when you re-enter the calibration page you'll always see the default values (not the latest inserted values).About Zwift, I suggest you to contact their customer care (we have been told that they had some issue in bluetooth)